The present invention generally relates to fastening systems, and, more particularly, to a pre-assembled fastening system having a fastener secured in a fastener retainer.
In assembly processes, seemingly simple operations can have a significant impact on overall assembly process efficiency. Often, such operations are very repetitive, being performed at many stages of assembly.
One such operation is the simple act of attaching one work piece to another using a threaded fastener. In the simple form of such an assembly operation, a bolt or the like is inserted through a hole in a first work piece, and is engaged in threads in a hole of a second work piece. It is known to provide the fastener in a grommet-like device, that can be inserted and held in the hole of the first work piece. In this way, the work piece with fastener can be pre-assembled, and when joined with the second work piece during the assembly process, the fastener is already in place for attaching the first and second work pieces together.
Fasteners with fastener retainers, often referred to as captive fasteners, have taken on different forms, with differing results. U.S. Pat. No. 5,395,194 entitled xe2x80x9cCONVOLUTED BOLT RETAINERxe2x80x9d, for example, discloses a polymer retainer having a thin wall body member comprising an alternate arrangement of ribs and ears about a central opening. The polymeric retainer is pre-assembled into a shaped bore in a structural member, and is retained therein by elastic deformation of the retainer walls. The elastic body member retains a bolt shaft disposed in the opening thereof, prior to mounting of the structural member on a mounting surface.
A disadvantage of this design, however, is that a special stepped bore is required in the structural member. As such, the retainer cannot be used with structures having conventional holes. An additional disadvantages is that fastener systems constructed in accordance with the design are not adequately retained in the structure, and can become dislodged during shipment.
Other captive fastening systems have fastener retention members that engage the threads of the fastener, such that the fastener must be more or less threaded into or out of the fastener retention member, to adjust the axial position of the fastener relative to the fastener retention member. This increases the time required to secure the fastener in the retention member, or to adjust the relative position of the fastener in the retention member.
It is desirable that the fastener retention member of a captive fastener system be securely retained in a hole of a work piece, without special shaping of the hole. It is further desirable that the fastener retention member grasp the fastener securely, at any position along the length of the fastener, whether at a threaded portion or at a smooth portion of the fastener shank, while still allowing axial adjustment of the fastener in the fastener retention member. Once seated in the hole, the fastener retention member should allow insertion or withdrawal of the fastener relative to the fastener retention member, without dislodging the fastener retention member. Further, it is desirable that the fastener retention members allow slight angular adjustment of the fastener within the hole in the work piece such that the captive fastener system compensates for slight misalignment between the first and second work pieces.
The present invention provides a captive fastening system in which a fastener is held in a fastener retention member by a plurality of inwardly directed elongated dimples that frictionally engage the outer surface of the fastener.
In one form thereof, the invention provides a captive fastener system, with a fastener including a head and a shank, and at least a portion of the shank having threads. A fastener retention member includes a cylindrical body having an axis and an axial opening therethrough. A flange is provided at one end of the cylindrical body extending radially outward from the axial opening. At least one work piece engagement member in the body is adapted and arranged to engage a bore in a work piece. A plurality of inwardly extending dimples is provided in the cylindrical body for frictionally engaging the fastener shank.
In another form thereof, the invention provides a fastener retention member with a cylindrical body having a first end and a second end, an axis and an axial opening therethrough between the first end and the second end. At least one inwardly extending, elongated dimple is provided in the body, the dimple being elongated generally in a direction between the first and second ends of the body.
In still another form thereof, the invention provides a fastener retention member with a substantially cylindrical body having a first end and a second end, and an axial opening between the first end and the second end. A flange extends outwardly of the body at one the end thereof. Pluralities of outwardly extending tabs are formed in the wall. A plurality of inwardly extending dimples is formed in the wall, each dimple being narrow in the circumferential direction of the cylindrical body and being elongated in the axial direction of the cylindrical body.